Trailer sway can create vehicle and trailer stability problems. Trailer sway occurs under specific conditions related to the location of the tow point of the trailer on the tow vehicle, the trailer weight applied at the trailer hitch and different loading of the trailer weight between the left and right trailer tires. Trailer sway is a condition in which the trailer swings in an oscillatory pattern side-to-side relative to the direction of the tow vehicle. The situation presents vehicle handling difficulties, where trailer sway can push the vehicle side-to-side, significantly increasing the risk of loss of control of the tow vehicle and or towed trailer.
Existing electronic anti sway systems focus on the tow vehicle, utilizing sensors and on board computers within the tow vehicle and then perform corrective actions within the tow vehicle to reduce the resulting sway of the tow vehicle. Relative to reducing sway at the trailer hitch various mechanical means exist which fall into two categories, weight distribution and anti sway hitches. These hitches use various mechanical means utilizing; torsion bars, rotating cams, actual movement of the hitch point and so forth to provide offsetting forces to reduce trailer sway. One electronic device exists which during a detected sway applies the trailer brakes, where testing reveals that applying all trailer brakes at the same time to reduce trailer sway is less effective than the individual control of left and right trailer brakes claimed in this invention.
When pulling a trailer where the trailer weight on the left tires and right tires are equal and where the weight on the trailer hitch is within a recommended range and where trailer tires are inflated properly and where the tow vehicle is also properly loaded then the trailer will follow directly behind the tow vehicle. When the weights within a trailer is not distributed evenly between the left tires and right tires or where lateral wind gusts occur due to the weather or large passing vehicles the trailer may begin to sway with increasing intensity to magnitudes which may eventually result in loss of control of the tow vehicle and or towed trailer.
Rather than offsetting the sway forces at the trailer hitch the only known electronic trailer sway device detects the trailer sway and then applies all the trailer brakes, where both left and right brakes are applied equally to dampen the sway where if the tow vehicle brakes are not applied, in theory the applied trailer brakes would attempt to pull the trailer, through braking friction, directly behind the tow vehicle. Although somewhat effective when tow vehicle brakes are not being applied, when the tow vehicle is also decelerating the equal braking on both left and right trailer brakes limits the ability to reduce trailer sway.
Although the various hitches are effective when these systems are installed and adjusted properly for a specific trailer and vehicle application, the purchase, installation and adjustment of anti sway hitches and other anti sway mechanisms results is relatively expensive system and thus these devices are in limited use.
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